Jetta King (EFI) started normally and turned off as soon as it refueled.

Troubleshooting of engine starting difficulty

Engine starting difficulty means that the starter can drive the engine to rotate at normal speed, and there are obvious signs of car collision, but it can't be started, or it needs multiple starts or long rotation to start. For the failure that is difficult to start, it is necessary to distinguish whether it occurs when the car is cold or hot, and whether it is cold or hot. The cause of this failure is usually in the fuel injection system.

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Fault phenomenon

When starting, the crankshaft speed is normal, but the starting time is long, or there are obvious signs of the car landing and it cannot be started.

2.

Cause of failure

Air leakage in the air intake system; Fuel pressure is too low; Air filter is blocked; Water temperature sensor failure; Air flowmeter failure; Idle speed control valve or additional air valve is faulty; Cold start injector does not work; Fuel injector leaks oil; Incorrect ignition timing; The line from the start switch to the computer is open; Cylinder compression pressure is too low.

3.

Fault diagnosis and elimination

(

1

) for fault self-diagnosis. If there is a fault code, find the corresponding fault cause according to the fault code.

(

2

)

Check the vacuum degree of intake pipe at idle speed. If the vacuum degree is less than

667

Kilopascal

, indicating that there is air leakage in the air intake system, check the joint, gasket, vacuum hose, exhaust gas recirculation system and fuel evaporation recovery system of the air intake pipe.

(

three

) Check the air filter. If the filter element is blocked, it should be cleaned or replaced.

(

four

If you step on the accelerator to the bottom.

1

/

four

The engine can be started normally when it is left and right, but it is difficult to start when the throttle is fully closed. Check whether the idle control valve and the additional air valve are working normally. Unplug the harness plug of the idle speed control valve when the cold car is idling, or clamp the air hose of the additional air valve with pliers when the cold car is idling. If the engine speed does not decrease, it means that the idle control valve is not working properly. Check the idle control valve and its control circuit.

(

five

) Check the fuel pressure. Short the two detection jacks of the electric gasoline pump with wires, and then turn on the ignition switch to make the electric gasoline pump run. In this state, the fuel pressure should reach

300

Kilopascal

About. If the pressure is too low, check whether the oil pressure regulator leaks oil, whether the gasoline filter is blocked and whether the maximum pump pressure of the gasoline pump is normal.

(

six

)

Check the water temperature sensor or air flow meter. Unplug the wiring harness plug of the water temperature sensor or the air flow meter, and measure the resistance between the terminals of the water temperature sensor and the air flow meter with a multimeter. If the resistance does not meet the standard, it should be replaced.

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seven

)

If it is difficult to start the car when it is cold and normal when it is hot, check whether the cold start injector works normally. First, check whether there is a cold start injector harness plug when starting.

12

V

Left and right voltage. If there is no voltage, the control circuit is faulty. Check the cold start temperature time switch and its control circuit. If there is voltage at the wiring harness plug when starting, check whether the electromagnetic coil resistance of the cold start injector is normal and whether the nozzle hole is blocked.

(

eight

)

If it is difficult to start in the hot car state, check whether the holding pressure of the fuel system is normal after the ignition switch is turned off. Connect the oil pressure gauge and measure the fuel pressure. After turning off the ignition switch (flameout),

five

department

Internal fuel pressure should be maintained at not less than

150

Kilopascal

About. If the pressure is too low, check the oil pressure regulator, electric gasoline pump and fuel injector for oil leakage.

(

nine

) Check the ignition timing at idle speed. If it does not meet the standard value, it should be adjusted.

(

10

) Check whether the startup signal from the startup switch to the computer is normal. If the computer can't receive the start signal of the start switch, it can't control the start enrichment, which will also lead to the start difficulty. In this regard, we need to check whether the signal to start the switch is transmitted from the computer harness plug to the computer. If there is no signal, check the starting switch and wiring.

(

1 1

) Check the cylinder compression pressure. If the pressure is too low, disassemble and check the engine.

(

12

If all the above tests are normal, you can try a new computer. If it is improved, it means that the original machine is faulty and should be replaced.